Ionization potential
Electrons are reluctant to leave: ionization potential. The graph shows the energy needed to remove an electron from each atom. What conclusions can you draw?
Electrons are reluctant to leave: ionization potential. If you hover the mouse over the periodic table you will see the energy needed to remove an electron from each atom; if you click on an atom, you will see its ionization potential and that of the atoms of its group. What conclusions can you draw?
The original interactive periodic table, made in Flash, no longer works in current browsers; the image shows one of its views.
The bars that go appearing on the graph show the energy that must be supplied to an element in a gaseous state to extract an electron from it. Even if you don't understand energy units, look at the relative height of the bars to compare the ionization potential of some elements with others.
- When going down the same group (column) of the periodic system, the atoms increase in size and the energy needed to extract the outermost electron decreases.
The easiest electron to remove from an atom is the outermost one. When moving down a group, the outermost electron is found in a layer increasingly distant from the core. That distance increasing between the outermost electron and the nucleus makes them attract less strongly and is, therefore, easier to remove an electron from an element the lower down we are in the periodic table.
- When going to the right in a period (row) of the periodic system, the atoms decrease in size, because the outermost electron is found closer to the core and it is more difficult to tear it off.
By progressing in a period, electrons are added to the same shell but also protons are added to the nucleus. The increase in protons makes the nucleus have a greater positive charge and thus strongly attract the electrons. The atomic orbitals are compressed from one atom to the next, thus decreasing its size progressively and it becomes more difficult to remove the outermost electron.